The relationship between the development of aversive nicotine withdrawal symptoms and the effectiveness of smoking treatment strategies is examined in a two phase study. The first phase establishes behavioral and physiological indicators and a time course for withdrawal symptoms. Smokers are deprived of nicotine after a baseline period of smoking. Severity of withdrawal symptoms are determined by a variety of physiological, subjective, and behavioral measures as related to baseline levels of daily nicotine intake observed under hospital conditions. In the second phase, smokers are recruited into a treatment program in which they undergo either abrupt cessation or gradual reduction of nicotine intake. The relationship between withdrawal symptom severity and degree of change in smoking patterns of subjects is examined in a treatment program.